Nexus 7, built directly for Google by Asus. I was a little skeptical about the purchase, generally being a fan of Apple and thus hesitant to try life with Android. I have to say that I have been delightfully surprised with how impressive the tablet has been. It is light, easy to read, very portable, and the latest form of the Android operating system (whimsically called "Jelly Bean" by Google) is pretty good. Not as polished and smooth as Apple's iOS by any means, but good enough. And the Nexus 7 costs only about 60% as much as an iPad Mini (which I have yet to see in the wild here in Spokane, Washington).
Several people I work with have been sporting Nexus 7s, and for good reason. The little tablet is a beast -- 2GB RAM and a quad-core processor! For just under $200. If you are interested in getting a smaller tablet and aren't committed to getting an iPad Mini, check out a Nexus 7. You might just like what you see.